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System Analysis and Design
B.FTech
Semester-IV
NIFT New Delhi

System Approach
Systems are created to solve problems.
One can think of the systems approach as
an organized way of dealing with a
problem.

OBJECTIVES
• understand a system
• understand the different phases of system
developments life cycle
• know the components of system analysis
• know the components of system designing

SYSTEM LIFE CYCLE
• System life cycle is an organizational
process of developing and maintaining
systems.
• It helps in establishing a system project
plan, because it gives overall list of
processes and sub-processes required
developing a system.

SDLC
• System development life cycle means
combination of various activities.

Following are the different phases of
software development cycle:
• System study
• Feasibility study
• System analysis
• System design
• Coding
• Testing
• Implementation
• Maintenance

The different phases of software development life
cycle is shown in Fig. A

System Study
• System study is the first stage of system
development life cycle
• System study is the first stage of system
development life cycle
• To describe the system study phase more
analytically, we would say that system study
phase passes through the following steps:
• problem identification and project initiation
• background analysis
• inference or findings

Feasibility Study
On the basis of result of the initial study,
feasibility study takes place.
• The feasibility study is basically the test of the
proposed system in the light of its workability,
meeting user’s requirements, effective use of
resources and the cost effectiveness
• The main goal of feasibility study is not to solve
the problem but to achieve the scope

System Analysis
• Assuming that a new system is to be developed,
the next phase is system analysis.
• Analysis involved a detailed study of the current
system, leading to specifications of a new
system.
• Analysis is a detailed study of various
operations performed by a system and their
relationships within and outside the system

System Analysis
• During analysis, data are collected on the
available files, decision points and transactions
handled by the present system.
• Interviews, on-site observation and
questionnaire are the tools used for system
analysis.
• Using the following steps it becomes easy to
draw the exact boundary of the new system
under consideration:
– Keeping in view the problems and new requirements
– Workout the pros and cons including new areas of the
system

System Analysis
• All procedures, requirements must be analysed and
documented in the form of detailed data flow diagrams
(DFDs), data dictionary, logical data structures and
miniature specifications.
• System Analysis also includes sub-dividing of complex
process involving the entire system, identification of data
store and manual processes.
• The main points to be discussed in system analysis are:
• Specification of what the new system is to accomplish based
on the user requirements.
• Functional hierarchy showing the functions to be performed by
the new system and their relationship with each other.
• Function network which are similar to function hierarchy but
they highlight the those functions which are common to more
than one procedure.
• List of attributes of the entities - these are the data items which
need to be held about each entity (record)

System Design
• Based on the user requirements and the detailed
analysis of a new system, the new system must
be designed.
• This is the phase of system designing. It is a
most crucial phase in the development of a
system.
• Normally, the design proceeds in two stages :
• preliminary or general design
• Structure or detailed design

There are several tools and techniques used for
designing. These tools and techniques are:
• Flowchart
• Data flow diagram (DFDs)
• Data dictionary
• Structured English
• Decision table
• Decision tree

Coding
• After designing the new system, the whole system is
required to be converted into computer understanding
language.
• Coding the new system into computer programming
language does this.
• It is an important stage where the defined procedure are
transformed into control specifications by the help of a
computer language.
• This is also called the programming phase in which the
programmer converts the program specifications into
computer instructions, which we refer as programs.
• The programs coordinate the data movements and
control the entire process in a system.

Testing
• Before actually implementing the new system
into operations, a test run of the system is done
removing all the bugs, if any.
• It is an important phase of a successful system.
After codifying the whole programs of the
system, a test plan should be developed and run
on a given set of test data.
• The output of the test run should match the
expected results.
• Using the test data following test run are carried
out:
– Unit test
– System test

Testing
• Unit test: When the programs have been coded and
compiled and brought to working conditions, they must
be individually tested with the prepared test data. Any
undesirable happening must be noted and debugged
(error corrections).
• System Test: After carrying out the unit test for each of
the programs of the system and when errors are
removed, then system test is done.
– At this stage the test is done on actual data. The complete
system is executed on the actual data.
– At each stage of the execution, the results or output of the
system is analysed.
– During the result analysis, it may be found that the outputs are
not matching the expected out of the system.
– In such case, the errors in the particular programs are identified
and are fixed and further tested for the expected output.

Implementation
• After having the user acceptance of the new system
developed, the implementation phase begins.
• Implementation is the stage of a project during which
theory is turned into practice.
• During this phase, all the programs of the system are
loaded onto the user's computer.
• After loading the system, training of the users starts.
Main topics of such type of training are:
• How to execute the package
• How to enter the data
• How to process the data (processing details)
• How to take out the reports

• After the users are trained about the computerized
system, manual working has to shift from manual to
computerized working. The following two strategies
are followed for running the system:
• Parallel run: In such run for a certain defined period, both the
systems i.e. computerized and manual are executed in parallel. This
strategy is helpful because of the following:
• Manual results can be compared with the results of the
computerized system.
• Failure of the computerized system at the early stage, does
not affect the working of the organization, because the
manual system continues to work, as it used to do.
– Pilot run: In this type of run, the new system is installed
in parts. Some part of the new system is installed first
and executed successfully for considerable time period.
When the results are found satisfactory then only other
parts are implemented. This strategy builds the
confidence and the errors are traced easily.

Maintenance
• Maintenance is necessary to eliminate errors in the
system during its working life and to tune the system to
any variations in its working environment.
• It has been seen that there are always some errors
found in the system that must be noted and corrected.
• It also means the review of the system from time to
time. The review of the system is done for:
– knowing the full capabilities of the system
– knowing the required changes or the additional requirements
– studying the performance
• If a major change to a system is needed, a new project
may have to be set up to carry out the change. The new
project will then proceed through all the above life cycle
phases.

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